The present invention relates to a method for transmitting outgoing useful signals and an outgoing clock signal from a transmitter via at least two line pairs to a receiver, and to a method for receiving incoming useful signals and an incoming clock signal from a transmitter via at least two line pairs, and to a transmitter and a receiver.
Outgoing useful signals representing digital information are transmitted for example between a memory controller and a memory component, between memory components and between other integrated circuits. The data rates used in this case are being increased further and further in accordance with the general trend in information technology. The data rate is determined, on the one hand, by the number of parallel lines between a transmitter and a receiver and, on the other hand, by the bit rate or bandwidth of the transmission on each individual line. In order that information represented in outgoing useful signals can be reliably recovered at the receiver end, an outgoing clock signal is typically transmitted at the same time. At the transmitter there is a well-defined phase relationship between the outgoing clock signal and the outgoing useful signals. At the receiver end, a clock is obtained from the outgoing clock signal and with application of an adjustable phase difference, the outgoing useful signals being sampled using the clock.
A number of parallel lines via which the outgoing useful signals are transmitted are conventionally provided for example between a memory controller and a memory component. The outgoing useful signals represent data, addresses or control commands, by way of example. In addition, one or a plurality of clock signal lines via which the outgoing clock signals are transmitted are provided. When a single clock signal line is used for a multiplicity of useful signal lines, the centrally received outgoing clock signal or the clock obtained therefrom must be distributed to all the receivers connected to the useful signal lines. Transmission of a respective outgoing clock signal for a small group (for example two or four) of useful signal lines results in an undesirable increase in the total number of lines and pins or contacts at the transmitter and at the receiver.
For these and other reasons, there is a need for the present invention.